How to Catch AI Hallucinations: A Copy-Paste Hallucination Checker Prompt (Tested)

You ask an AI a question. It answers in fluent, confident prose — complete with a study, a percentage, and a name. Some of it is wrong, and nothing about the wording tells you which part. That's the whole problem with hallucinations: the errors wear the same suit as the facts. The fix is not "trust it less" in some vague way. The fix is a repeatable audit step between AI wrote it and I used it . Below is a short hallucination checker prompt you can copy right now, a test run showing what it catches and what slips past it, and an honest account of where a one-liner stops being enough. What counts as an AI hallucination? Not every mistake is a hallucination. A useful working definition: a hallucination is a claim the model states as fact that has no grounding in reality or in your source material. The common shapes: Fabricated citations — a named study, expert, or paper that doesn't exist. Often dressed with a year and an institution. Plausible-but-wrong specifics — dates, version numbers, statistics that are almost right, which makes them worse. Confident category errors — mixing up two similar things (a library and a framework, one company's product and another's). Invented consensus — "experts widely agree that…" with no experts attached. The dangerous ones are the middle two. Obvious nonsense filters itself; a wrong year in a fluent paragraph does not. The copy-paste hallucination checker prompt Here is the short version, free, no strings. It works on ChatGPT, Claude, or any capable model — paste it into a fresh chat, then paste the answer you want audited: Audit the text below for hallucinations. Do not add new information. 1. Extract every factual claim as a separate numbered line. 2. Label each claim: VERIFIABLE (state how to check it), SUSPECT (state what makes it doubtful), or FABRICATION-PATTERN (named source/study/number with no citation). 3. Flag every name, number, date, and citation for manual checking. 4. Finish with the 3 claims most likely to be wrong